All solid state secondary-battery additive, all-solid-state secondary battery, and method for producing same

Abstract

General Formula (I) Provided is an all solid state secondary-battery additive comprising a polyalkylene carbonate (I) represented by general formula (I), and by providing such additive, properties such as the charge-discharge capacity and interfacial resistance of an all-solid-state secondary battery are improved. (In general formula (I), R 1 and R 2 are each a C1-10 chain-like alkylene group or C3-10 cycloalkylene group, m is 0, 1, or 2 and n is an integer of 10 to 15000, and each R 1 , R 2 and m in the polyalkylene carbonate (I) chain is independently the same or different.)

The invention claimed is: 
     
       1. An all-solid secondary battery comprising a positive electrode, a negative electrode and a solid electrolyte layer positioned between the positive electrode and the negative electrode,
 wherein the solid electrolyte layer comprises an additive in a range of 0.5 to 20 mass % relative to the solid electrolyte layer, 
 wherein the additive comprises a polyalkylene carbonate, 
 wherein the polyalkylene carbonate has an alkylene carbonate moiety (II) represented by general formula (II): 
 
       
         
           
           
               
               
           
         
         wherein in the formula (II), R 1  is a chain alkylene group having 1 to 10 carbon atoms or a cycloalkylene group having 3 to 10 carbon atoms and optionally an alkylene glycol moiety (III) represented by general formula (III): 
       
       
         
           
           
               
               
           
         
         wherein in the formula (III), R 2  is a chain alkylene group having 1 to 10 carbon atoms or a cycloalkylene group having 3 to 10 carbon atoms, m is 0, 1 or 2 and each of R 2  in the alkylene glycol moiety (III) is the same or different. 
       
     
     
       2. The all-solid secondary battery according to  claim 1 ,
 wherein the polyalkylene carbonate is a polyalkylene carbonate (I) represented by the general formula (I): 
 
       
         
           
           
               
               
           
         
         wherein in the formula (I), each of R 1  and R 2  is a chain alkylene group having 1 to 10 carbon atoms or a cycloalkylene group having 3 to 10 carbon atoms, m is 0, 1 or 2, n is an integer of 10 to 15000, 
         each of R 1 , R 2  and m in the polyalkylene carbonate (I) chain is independently the same or different. 
       
     
     
       3. The all-solid secondary battery according to  claim 1 , wherein each of R 1  and R 2  is an ethylene group, a propylene group or a cyclohexylene group. 
     
     
       4. The all-solid secondary battery according to  claim 1 ,
 wherein the additive further comprises an alkali metal salt. 
 
     
     
       5. The all-solid secondary battery according to  claim 4 , wherein the alkali metal salt is at least one selected from lithium chloride, lithium hydroxide, lithium iodide, lithium acetate, lithium nitrate, lithium benzoate and cesium chloride. 
     
     
       6. The all-solid secondary battery according to  claim 1 ,
 wherein the additive further comprises polyalkylene glycol. 
 
     
     
       7. A solid electrolyte layer for an all-solid secondary battery comprising a positive electrode, a negative electrode and the solid electrolyte layer positioned between the positive electrode and the negative electrode,
 characterized in that the solid electrolyte layer comprises a heat-decomposed product of an additive comprising polyalkylene carbonate and a solid electrolyte, 
 wherein the polyalkylene carbonate has an alkylene carbonate moiety (II) represented by general formula (II): 
 
       
         
           
           
               
               
           
         
         wherein the formula (II), R 1  is a chain alkylene group having 1 to 10 carbon atoms or a cycloalkylene group having 3 to 10 carbon atoms and 
         optionally an alkylene glycol moiety (III) represented by general formula (III): 
       
       
         
           
           
               
               
           
         
         wherein the formula (III), R 2  is a chain alkylene group having 1 to 10 carbon atoms or a cycloalkylene group having 3 to 10 carbon atoms, m is 0, 1 or 2 and each of R 2  in the alkylene glycol moiety (III) is the same or different. 
       
     
     
       8. The solid electrolyte layer according to  claim 7 , wherein the solid electrolyte is an inorganic solid electrolyte selected from Z 2 S-M x S y  wherein Z is one or more selected from Li and Na, M is one or more selected from P, Si, Ge, B, Al and Ga, and x and y are numbers giving stoichiometric ratios depending on the type of M, Z 2 S-M n S m -ZX, wherein Z is one or more selected from Li and Na, M is one or more selected from P, Si, Ge, B, Al and Ga, X is one or more selected from Cl, Br and I, and n and m are numbers giving stoichiometric ratios depending on the type of M, Li 3x La 2/3−x TiO 3  wherein 0<x<0.17, Li 1+x Al x Ti 2-x (PO 4 ) 3  wherein 0<x<2, Li 7 La 3 Zr 2 O 12  and Li 1+x Al x Ge 2−x (PO 4 ) 3  wherein 0<x<2. 
     
     
       9. A positive electrode for an all-solid secondary battery comprising the positive electrode, a negative electrode and a solid electrolyte layer positioned between the positive electrode and the negative electrode,
 characterized in that the positive electrode comprises a positive electrode active material, a solid electrolyte and a heat-decomposed product of an additive comprising polyalkylene carbonate, 
 wherein the polyalkylene carbonate has an alkylene carbonate moiety (II) represented by general formula (II): 
 
       
         
           
           
               
               
           
         
         wherein the formula (II), R 1  is a chain alkylene group having 1 to 10 carbon atoms or a cycloalkylene group having 3 to 10 carbon atoms and optionally an alkylene glycol moiety (III) represented by general formula (III): 
       
       
         
           
           
               
               
           
         
         wherein the formula (III), R 2  is a chain alkylene group having 1 to 10 carbon atoms or a cycloalkylene group having 3 to 10 carbon atoms, m is 0, 1 or 2 and each of R 2  in the alkylene glycol moiety (III) is the same or different. 
       
     
     
       10. A negative electrode for an all-solid secondary battery comprising a positive electrode, the negative electrode and a solid electrolyte layer positioned between the positive electrode and the negative electrode,
 characterized in that the negative electrode comprises a negative electrode active material, a solid electrolyte and a heat-decomposed product of an additive comprising polyalkylene carbonate, 
 wherein the polyalkylene carbonate has an alkylene carbonate moiety (II) represented by general formula (II): 
 
       
         
           
           
               
               
           
         
         wherein the formula (II), R 1  is a chain alkylene group having 1 to 10 carbon atoms or a cycloalkylene group having 3 to 10 carbon atoms and 
         optionally an alkylene glycol moiety (III) represented by general formula (III): 
       
       
         
           
           
               
               
           
         
         wherein the formula (III), R 2  is a chain alkylene group having 1 to 10 carbon atoms or a cycloalkylene group having 3 to 10 carbon atoms, m is 0, 1 or 2 and each of R 2  in the alkylene glycol moiety (III) is the same or different. 
       
     
     
       11. A producing method of an all-solid secondary battery characterized in comprising
 a step of obtaining a solid electrolyte slurry by dissolving or dispersing a solid electrolyte and an additive comprising polyalkylene carbonate in an organic solvent; 
 a step of obtaining a positive electrode slurry by dissolving or dispersing the additive, a solid electrolyte and a positive electrode active material in an organic solvent, 
 a step of obtaining a negative electrode slurry by dissolving or dispersing the additive, a solid electrolyte and a negative electrode active material in an organic solvent, 
 a step of obtaining a solid electrolyte layer, a positive electrode and a negative electrode by coating and drying each of the slurries on a substrate, 
 a step of obtaining a laminate by laminating the solid electrolyte layer, the positive electrode and the negative electrode; and 
 a step of heat-treating the laminate to heat-decompose the additive; 
 wherein the polyalkylene carbonate has an alkylene carbonate moiety (II) represented by general formula (II): 
 
       
         
           
           
               
               
           
         
         wherein the formula (II), R 1  is a chain alkylene group having 1 to 10 carbon atoms or a cycloalkylene group having 3 to 10 carbon atoms and 
         optionally an alkylene glycol moiety (III) represented by general formula (III): 
       
       
         
           
           
               
               
           
         
         wherein the formula (III), R 2  is a chain alkylene group having 1 to 10 carbon atoms or a cycloalkylene group having 3 to 10 carbon atoms, m is 0, 1 or 2 and each of R 2  in the alkylene glycol moiety (III) is the same or different. 
       
     
     
       12. The producing method of an all-solid secondary battery according to  claim 11 ,
 wherein the solid electrolyte is Li 2 S—P 2 S 5  and each of R 1  and R 2  is an ethylene group, a propylene group or a cyclohexylene group. 
 
     
     
       13. The producing method of an all-solid secondary battery according to  claim 11 ,
 wherein the heat-treating is performed at a temperature between T−25° C. and T+50° C. where T is a decomposition starting temperature of the additive, and 
 wherein the thermal decomposition starting temperature is a temperature at intersection of tangential line before starting the weight loss and the tangential line drawn such that the gradient between the inflection points in the decomposition curve is maximized where the horizontal axis is temperature and the vertical axis is the weight ratio of the sample (TG %), in the heat treatment of the additive under a nitrogen atmosphere at a heating rate of 10° C./min from room temperature to 500° C. 
 
     
     
       14. The producing method of an all-solid secondary battery according to  claim 11 ,
 wherein the inorganic solid electrolyte is selected from Z 2 S-M x S y  wherein Z is one or more selected from Li and Na, M is one or more selected from P, Si, Ge, B, Al and Ga, and x and y are numbers giving stoichiometric ratios depending on the type of M, Z 2 S-M n S m -ZX wherein Z is one or more selected from Li and Na, M is one or more selected from P, Si, Ge, B, Al and Ga, X is one or more selected from Cl, Br and I, and n and m are numbers giving stoichiometric ratios depending on the type of M, Li 3x La 2/3−x TiO 3  wherein 0<x<0.17, Li 1+x Al x Ti 2−x (PO 4 ) 3  wherein 0<x<2, Li 7 La 3 Zr 2 O 12  and Li 1+x Al x Ge 2−x (PO 4 ) 3  wherein 0<x<2.